1. Field of the Invention
This invention relates to 1,3-dialkyl-2-imidazolidinones and a manufacturing process therefor.
1,3-Dialkyl-2-imidazolidinones have been extensively used as, for example, an aprotic polar solvent; for example, they are useful as a solvent for a resin such as polyamide, polystyrene, polyester, polyvinyl chloride or a phenol resin; a reaction solvent for various kinds of organic syntheses; or an extraction solvent for extracting an aromatic hydrocarbon from an aliphatic hydrocarbon. Among 1,3-dialkyl-2-imidazolidinones, 1,3-dimethyl-2-imidazolidinone (hereinafter, referred to as xe2x80x9cIDMIxe2x80x9d) is particularly useful because it is remarkably resistant to a strong base, is little decomposed when heated with a solution of an alkali-metal hydroxide, and therefore, is suitably used as a reaction solvent for dehalogenation of an aromatic organic halide, in particular polychlorobiphenyls.
2. Description of the Prior Art
Various preparation processes for 1,3-dialkyl-2-imidazolidinones have been suggested, in which N,Nxe2x80x2-dialkylethylenediamine is involved as a starting material; for example, reacting N,Nxe2x80x2-dimethylethylenediamine with trichloromethyl chloroformate as disclosed in JP-A 53-73561; reacting N,Nxe2x80x2-dimethylethylenediamine with carbon dioxide as disclosed in JP-A 57-175170; reacting N,Nxe2x80x2-dialkylethylenediamine with phosgene in the presence of water and dehydrochlorinating agent as disclosed in JP-As 61-109772 and 61-172862; reacting N,Nxe2x80x2-dimethylethylenediamine with urea in the presence of a polar solvent as disclosed in JP-A 7-252230. As the starting material, N,Nxe2x80x2-dimethylethylenediamine can be prepared by a well-known process, in which ethylene dichloride and monomethylamine are reacted as described in JP-A 57-120570. The process involves a problem of disposing a large amount of byproduct, sodium chloride contaminated by organic compounds. A reaction of ethylene glycol with monomethylamine in the presence of a homogeneous catalyst consisting of ruthenium and triphenylphosphine has been suggested to prepare N,Nxe2x80x2-dimethylethylenediamine as disclosed in J.Organometallic Chem., Vol.407, p.97 (1991). It is, however, difficult to industrially recover and recycle such a homogeneous precious metal catalyst. Thus, it cannot be said to be ideal to produce 1,3-dialkyl-2-imidazolidinone from N,Nxe2x80x2-dialkylethylenediamine.
There have been suggested a reductive addition of 2-imidazolidinone and formaldehyde in the presence of a hydrogenating catalyst (JP-A 60-243071) and a catalytic reduction of dialkyl ether of N,Nxe2x80x2-hydroxymethylimidazolidinone (JP-B 60-3299) as another attempt to prepare N,Nxe2x80x2-dialkylimidazolinones. These also involve the above problem because a starting material is prepared from dimethylethylenediamine, and are impractical because its processes are lengthy.
There have been disclosed interesting processes, i.e., reactions of N-alkylmonoethanolamine with an alkylamine such as monomethylamine, and with carbon dioxide, alkylcarbamate alkylamine salt or 1,3-dialkylurea (JP-A 57-98268); a reaction of ethylene glycol with carbon dioxide and monomethylamine at an elevated temperature and a higher pressure (JP-A 59-155364); and a reaction of ethylene carbonate with monoalkylamine (WO96/02516). These may be promising DMI preparation processes because they are a one-step reaction and the starting materials, i.e., N-alkylmonoethanolamine, ethylene glycol and ethylene carbonate, can be readily prepared from ethylene oxide with minimal byproducts. Based on our findings, however, a large amount of black solid is formed in these processes, which may block up a line during recycling all or a part of high boiling products into a reactor after collection of 1,3-dialkyl-2-imidazolidinone. These processes are, therefore, industrially impractical and thus have not been industrialized.
In addition, 1,3-dialkyl-2-imidazolidinones prepared according to these processes contain not a little amount of N-alkylformamide as an impurity, and thus are not suitable for use as a solvent.
Furthermore, commercially available DMI contains 1-methoxymethyl-3-methyl-2-imidazolidinone as an impurity, which may cause problems such as a reduced yield and a formation of byproducts when used as a reaction solvent or a polymerization solvent.
Thus, an object of this invention is to provide a process for manufacturing 1,3-dialkyl-2-imidazolidinones in a direct one-step reaction from industrially available alkylene carbonate, N-alkylmonoethanolamine or 1,2-diol, which can minimize forming solid materials and be readily conducted in an industrial large-scale production with a higher yield and less byproducts; as well as 1,3-dialkyl-2-imidazolidinone containing a minimal amount of 1-methoxymethyl-3-methyl-2-imidazolidinone according to the process.
We have intensely investigated a method for minimizing 1-alkoxyalkyl-3-alkyl-2-imidazolidinones as an impurity in 1,3-dialkyl-2-imidazolidinones and reducing formation of solid during the reaction, and have finally found that solid formation may be reduced, 1,3-dialkyl-2-imidazolidinones may be produced in a higher yield and 1-alkoxyalkyl-3-alkyl-2-imidazolidinones can be minimized by heating alkylene carbonate, N-alkylmonoethanolamine or ethylene glycol with monoalkylamine and carbon dioxide, alkylcarbamate alkylamine salt, and/or 1,3-dialkylurea at 50xc2x0 C. or higher in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses.
Specifically, this invention provides;
(A) 1,3-dialkyl-2-imidazolidinones represented by general formula (1): 
wherein R1 is hydrogen or C1-C6 alkyl and R2 is C1-C6 alkyl, containing 50 ppm by weight or less of 1-alkoxyalkyl-3-alkyl-2-imidazolidinones represented by general formula (2): 
wherein R1 and R2 are as defined above; and R3 is C1-C6 alkylene; or general formula (3): 
wherein R1, R2 and R3 are as defined above;
(B) 1,3-dimethyl-2-imidazolidinone containing 50 ppm by weight or less of 1-methoxymethyl-3-methyl-2-imidazolidinone;
(C) 1,3-dialkyl-2-imidazolidinones described in (A) containing 0.5 wt % or less of N-alkylformamide represented by general formula (4):
R2NHCHOxe2x80x83xe2x80x83(4)
wherein R2 is as defined above;
(D) 1,3-dimethyl-2-imidazolidinone described in (B) containing 0.5 wt % or less of N-methylformamide;
(E) a process for manufacturing 1,3-dialkyl-2-imidazolidinones described in (A) or (C), comprising heating at 50xc2x0 C. or higher alkylene carbonate represented by general formula (5): 
wherein R1 is as defined above, with monoalkylamine represented by general formula (6):
R2NH2xe2x80x83xe2x80x83(6)
wherein R2 is as defined above; alkylcarbamate alkylamine salt represented by general formula (7):
R2NHCOOH.R2NH2xe2x80x83xe2x80x83(7)
wherein R2 is as defined above; and/or 1,3-dialkylurea represented by general formula (8):
R2NHCONHR2xe2x80x83xe2x80x83(8)
wherein R2 is as defined above; in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses;
(F) a process described in (E) where the reaction is conducted in the presence of carbon dioxide;
(G) a process for manufacturing 1,3-dialkyl-2-imidazolidinones described in (A) or (C), comprising heating at 50xc2x0 C. or higher N-alkylmonoethanolamine represented by general formula (9): 
wherein R1 and R2 are as defined above; with
i) monoalkylamine represented by general formula (6) and carbon dioxide,
ii) alkylcarbamate alkylamine salt represented by general formula (7), and/or
iii) 1,3-dialkylurea represented by general formula (8), in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses;
(H) a process for manufacturing 1,3-dialkyl-2-imidazolidinones described in (A) or (C), comprising heating at 50xc2x0 C. or higher N-alkylmonoethanolamine represented by general formula (9) with alkylcarbamate alkylamine salt represented by general formula (7) and/or 1,3-dialkylurea represented by general formula (8) in the presence of carbon dioxide, in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses;
(I) a process for manufacturing 1,3-dialkyl-2-imidazolidinones described in (A) or (C), comprising heating at 50xc2x0 C. or higher 1,2-diol represented by general formula (10): 
wherein R1 is as defined above; with
i) monoalkylamine represented by general formula (6) and carbon dioxide,
ii) alkylcarbamate alkylamine salt represented by general formula (7), and/or
iii) 1,3-dialkylurea represented by general formula (8), in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses;
(J) a process for manufacturing 1,3-dialkyl-2-imidazolidinones described in (A) or (C), comprising heating at 50xc2x0 C. or higher 1, 2-diol represented by general formula (10) with alkylcarbamate alkylamine salt represented by general formula (7) and/or 1,3-dialkylurea represented by general formula (8) in the presence of carbon dioxide, in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses;
(K) a process described in (E) for manufacturing 1,3-dimethyl-2-imidazolidinone described in (B) or (D), where alkylene carbonate is ethylene carbonate; monoalkylamine is monomethylamine; alkylcarbamate alkylamine salt is methylcarbamate methylamine salt; and 1,3-dialkylurea is 1,3-dimethylurea;
(L) a process described in (K) where the reaction is conducted in the presence of carbon dioxide;
(M) a process described in (G) for manufacturing 1,3-dimethyl-2-imidazolidinone described in (B) or (D), where N-alkylmonoethanolamine is 2-(methylamino)ethanol; monoalkylamine is monomethylamine; alkylcarbamate alkylamine salt is methylcarbamate methylamine salt; and 1,3-dialkylurea is 1,3-dimethylurea;
(N) a process described in (H) for manufacturing 1,3-dimethyl-2-imidazolidinone described in (B) or (D), wherein N-alkylmonoethanolamine is 2-(methylamino)ethanol; alkylcarbamate alkylamine salt is methylcarbamate methylamine salt; and 1,3-dialkylurea is 1,3-dimethylurea;
(O) a process described in (I) for manufacturing 1,3-dimethyl-2-imidazolidinone described in (B) or (D), wherein 1,2-diol is ethylene glycol; monoalkylamine is monomethylamine; alkylcarbamate alkylamine salt is methylcarbamate methylamine salt; and 1,3-dialkylurea is 1,3-dimethylurea;
(P) a process described in (J) for manufacturing 1,3-dimethyl-2-imidazolidinone described in (B) or (D), wherein 1,2-diol is ethylene glycol; alkylcarbamate alkylamine salt is methylcarbamate methylamine salt; and 1,3-dialkylurea is 1,3-dimethylurea;
(Q) a process described in any one of (E) to (P) where the reactor made of a metal comprising titanium or zirconium and/or an oxide thereof is a reactor which wholly consists of a metal comprising titanium or zirconium, or at least part of whose inside wall is coated with a metal comprising titanium or zirconium and/or an oxide thereof;
(R) a process described in (Q) where the reactor, at least part of the inside wall of which is coated with a metal comprising titanium or zirconium, is the reactor which is coated using a process selected from the group consisting of cladding processes such as rolling, explosive compaction, explosive rolling and casting rolling as well as baking process;
(S) a process described in (Q) where the reactor, at least part of the inside wall of which is coated with an oxide of a metal comprising titanium or zirconium, is the reactor which is coated using a method of forming an oxide film using an oxidizing agent;
(T) a process described in (Q) where the reactor, at least part of the inside wall of which is coated with an oxide of a metal comprising titanium or zirconium, is the reactor which is coated by means of thermal decomposition;
(U) a process described in any one of (E) to (P) where the metal comprising titanium or zirconium is selected from the group consisting of industrial pure titanium, corrosive resistant titanium-alloy and pure zirconium;
(V) a process described in any one of (E) to (P) where the reaction is conducted by heating at 100 to 300xc2x0 C.; and
(W) a process described in any one of (E) to (P) where 1,3-dialkyl-2-imidazolidinones represented by general formula (1) or water is used as a solvent.
According to the process of this invention, 1,3-dialkyl-2-imidazolidinones can be industrially effectively and readily produced. Furthermore, the process of this invention has a prominent characteristic that byproducts such as sodium chloride contaminated with organic compounds are not formed as in a conventional process.
This invention will be described in detail.
This invention provides 1,3-dialkyl-2-imidazolidinones represented by general formula (1) containing 50 ppm or less of 1-alkoxyalkyl-3-alkyl-2-imidazolidinone represented by general formula (2) or (3).
In such formulas, R1 is hydrogen or C1-C6 alkyl, R2 is C1-C6 alkyl and R3 is C1-C6 alkylene. Examples of 1-alkoxyalkyl-3-alkyl-2-imidazolidinone and 1-methoxymethyl-3-methyl-2-imidazolidinone, 1-methoxymethyl-3,4-dimethyl-2-imidazolidinone, 1-methoxymethyl-3,5-dimethyl-2-imidazolidinone, 1-(1-ethoxyethyl)-3-ethyl-2-imidazolidinone, 1-(2-ethoxyethyl)-3-ethyl-2-imidazolidinone, 1-(1-ethoxyethyl)-3-ethyl-4-methyl-2-imidazolidinone and 1-(2-ethoxyethyl)-3-ethyl-4-methyl-2-imidazolidinone.
Examples of 1,3-dialkyl-2-imidazolidinones are 1,3-dimethyl-2-imidazolidinone, 1,3,4-trimethyl-2-imidazolidinone, 1,3-dimethyl-4-ethyl-2-imidazolidinone, 1,3-dimethyl-4-isopropyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diethyl-4-methyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone, 1,3-diisopropyl-4-methyl-2-imidazolidinone, 1,3-di-n-propyl-2-imidazolidinone, 1,3-di-n-propyl-4-methyl-2-imidazolidinone, 1,3-di-tert-butyl-2-imidazolidinone and 1,3-di-tert-butyl-4-methyl-2-imidazolidinone.
Preferably, 1-methoxymethyl-3-methyl-2-imidazolidinone can be used as 1-alkoxyalkyl-3-alkyl-2-imidazolidinone and 1,3-dimethyl-2-imidazolidinone can be used as 1,3-dialkyl-2-imidazolidinone. Thus, 1,3-dimethyl-2-imidazolidinone containing 50 ppm or less of 1-methoxymethyl-3-methyl-2-imidazolidinone is most preferable.
Furthermore, 1,3-dialkyl-2-imidazolidinone containing 0.5 wt % or less of N-alkylformamide represented by general formula (4) is preferable. Examples of N-alkylformamide are N-methylformamide, N-ethylformamide, N-isopropylformamide, N-n-propylformamide and N-tert-butylformamide; preferably N-methylformamide. Thus, 1,3-dimethyl-2-imidazolidinone containing 50 ppm or less of 1-methoxymethyl-3-methyl-2-imidazolidinone and 0.5 wt % or less of N-methylformamide is most preferable.
In this invention, 1,3-dialkyl-2-imidazolidinones can be prepared by heating at 50xc2x0 C. or higher alkylene carbonate represented by general formula (5), with i) monoalkylamine represented by general formula (6), ii) alkylcarbamate alkylamine salt represented by general formula (7), and/or iii) 1,3-dialkylurea represented by general formula (8), in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses.
Alkylene carbonates represented by general formula (5) used as a starting material in the process of this invention include those in which R1 is hydrogen or C1-C6 alkyl, such as ethylene carbonate and propylene carbonate, which may be readily prepared by heating carbon dioxide and alkylene oxide in the presence of a catalyst such as a quarternary ammonium salt. A commercially available alkylene carbonate may be used as it is in the process of this invention or it may be subject to a common purification process such as distillation before being used in the reaction.
Examples of monoalkylamines represented by general formula (6) as an another material in the process of this invention are those in which R2 is C1-C6 alkyl, such as monomethylamine, monoethylamine, mono-n-propylamine, mono-isopropylamine, mono-n-butylamine, mono-sec-butylamine, mono-isobutylamine, mono-tert-butylamine and monocyclohexylamine; preferably monomethylamine and monoethylamine; more preferably monomethylamine.
The amount of monoalkylamine is generally, but not limited to, 0.1 to 200 moles, preferably 0.5 to 80 moles, more preferably 1.0 to 40 moles per one mole of alkylene carbonate.
Examples of alkylcarbamate alkylamine salt represented by general formual (7) as another material in the process of this invention are those in which R 2 is C1-C6 alkyl, such as methylcarbamate methylamine salt, ethylcarbamate ethylamine salt, n-propylcarbamate n-propylamine salt, isopropylcarbamate isopropylamine salt, n-butylcarbamate n-butylamine salt, sec-butylcarbamate secbutylamine salt, isobutylcarbamate isobutylamine salt, tert-butylcarbamate tert-butylamine salt and cyclohexylcarbamate cyclohexylamine salt, preferably methcarbamate methylamime salt and ethylcarbamate ethylamine salt; more preferably methylcarbamate methylamine salt.
Such alkylcarbamate alkylamine salt may be used as a solid or a solution such as an aqueous solution, or may be used as a combination of components generating the salt in the reaction system.
The amount of alkylcarbamate alkylamine salt is generally, but not limited to, 0.1 to 100 moles, preferably 0.5 to 40 moles, more preferably 1.0 to 20 moles per one mole of alkylene carbonate.
Examples of 1,3-dialkylurea represented by general formula (8) as an another material in the process of this invention are those in which R2 is C1-C6 alkyl, such as 1,3-dimethylurea, 1,3-diethylurea, 1,3-di-n-propylurea, 1,3-di-isopropylurea, 1,3-di-n-butylurea, 1,3-di-sec-butylurea, 1,3-di-isobutylurea, 1,3-di-tert-butylurea and 1,3-dicyclohexylurea; preferably 1,3-dimethylurea and 1,3-diethylurea; more preferably 1,3-dimethylurea.
Commercially available 1,3-dialkylurea man be used as it is, or a combination of components generating 1,3-dialkylurea in the reaction system may be employed.
Carbon dioxide may be used as a gaseous, liquid or solid state in the process of this invention, or an inorganic carbonate such as ammonium carbonate, which provides carbon dioxide during the reaction, may be employed. The amount of carbon dioxide is generally, but not limited to, 0.1 to 1000 moles, preferably 1 to 1500 moles per one mole of alkylene carbonate.
Monoalkylamine, alkylcarbamate alkylamine salt and 1,3-dialkylurea may be used alone or concurrently or as a mixture.
Most preferably, ethylene carbonate can be used as an alkylene carbonate, monomethylamine can be used as a monoalkylamine, methylcarbamate methylamine salt can be used as an alkylcarbamate alkylamine salt and 1,3-dimethylurea can be used as a 1,3-dialkylurea, in the light of extensive applications of the product DMI therefrom as a solvent.
According to this invention, 1,3-dialkyl-2-imidazolidinones can be prepared by heating at 50xc2x0 C. or higher N-alkylmonoethanolamine represented by general formula (9) with i) monoalkylamine represented by general formula (6) and carbon dioxide, ii) alkylcarbamate alkylamine salt represented by general formula (7) and/or iii) 1,3-dialkylurea represented by general formula (8), in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses.
Examples of N-alkylmonoethanolamine represented by general formula (9) as a material in the process of this invention are those in which R1 is hydrogen or C1-C6 alkyl and R2 is C1-C6 alkyl, such as 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(n-propylamino)ethanol, 2-(isopropylamino)ethanol, 2-(n-butylamino)ethanol, 2-(sec-butylamino)ethanol, 2-(isobutylamino)ethanol, 2-(tert-butylamino)ethanol, 2-(n-amylamino)ethanol, 2-(isoamylamino)ethanol, 2-(2-methylbutylamino)ethanol, 2-(1-methylbutylamino)ethanol, 2-(n-hexylamino)ethanol, n-cyclohexylethanolamine, 1-methylamino-2-propanol, 1-ethylamino-2-propanol, 1-(n-propylamino)-2-propanol, 1-(isopropylamino)-2-propanol, 1-(n-butylamino)-2-propanol, 1-(n-amylamino)-2-propanol, 1-methylamino-2-butanol, 1-methylamino-2-pentanol, 1-methylamino-2-hexanol and 1-methylamino-2-octanol; preferably 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(isopropylamino)ethanol and 1-methylamino-2-propanol; more preferably 2-(methylamino)ethanol.
Commercially available N-alkylmonoethanolamine may be used as it is, or may be subject to a common purification process such as distillation before being used in the reaction.
Monoalkylamine represented by general formula (6) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 100 moles, preferably 0.3 to 40 moles, more preferably 0.5 to 20 moles per one mole of N-alkylmonoethanolamine.
The amount of carbon dioxide is generally, but not limited to, 0.1 to 200 moles, preferably 1 to 100 moles per one mole of N-alkylmonoethanolamine.
Alkylcarbamate alkylamine salt represented by general formula (7) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 50 moles, preferably 0.3 to 20 moles, more preferably 0.5 to 10 moles per one mole of N-alkylmonoethanolamine.
Then, 1,3-dialkylurea represented by general formula (8) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 50 moles, preferably 0.3 to 20 moles, more preferably 0.5 to 10 moles per one mole of N-alkylmonoethanolamine.
(a)Monoalkylamine and carbon dioxide, (b)alkylcarbamate alkylamine salt and (c)1,3-dialkylurea may be used alone or concurrently or as a mixture.
Most preferably, 2-(methylamino)ethanol can be used as a N-alkylmonoethanolamine, monomethylamine can be used as a monoalkylamine, methylcarbamate methylamine salt can be used as an alkylcarbamate alkylamine salt and 1,3-dimethylurea can be used as a 1,3-dialkylurea, in the light of extensive applications of the product DMI therefrom as a solvent.
According to this invention, 1,3-dialkyl-2-imidazolidinones can be prepared by heating at 50xc2x0 C. or higher N-alkylmonoethanolamine represented by general formula (9) with alkylcarbamate alkylamine salt represented by general formula (7) and/or 1,3-dialkylurea represented by general formula (8) in the presence of carbon dioxide, in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glass.
N-alkylmonoethanolamine represented by general formula (9) used as a starting material in this invention process may be the same as described above.
Alkylcarbamate alkylamine salt represented by general formula (7) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 50 moles, preferably 0.3 to 20 moles, more preferably 0.5 to 10 moles per one mole of N-alkylmonoethanolamine.
1,3-Dialkylurea represented by general formula (8) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 50 moles, preferably 0.3 to 20 moles, more preferably 0.5 to 10 moles per one mole of N-alkylmonoethanolamine.
This reaction is preferably conducted in an atmosphere of carbon dioxide. The amount of carbon dioxide is generally, but not limited to, 0.1 to 1000 moles, preferably 1 to 500 moles per one mole of N-alkylmonoethanolamine.
Alkylcarbamate alkylamine salt and 1,3-dialkylurea may be used alone or concurrently or as a mixture.
Most preferably, 2-(methylamino)ethanol can be used as an N-alkylmonoethanolamine, methylcarbamate methylamine salt can be used as an alkylcarbamate alkylamine salt and 1,3-dimethylurea can be used as a 1,3-dialkylurea, in the light of extensive applications of the product DMI therefrom as a solvent.
According to this invention, 1,3-dialkyl-2-imidazolidinones can be also prepared by heating at 50xc2x0 C. or higher 1,2-diol represented by general formula (10) with i) monoalkylamine represented by general formula (6) and carbon dioxide, ii) alkylcarbamate alkylamine salt represented by general formula (7) and/or iii) 1,3-dialkylurea represented by general formula (8), in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glass.
Examples of 1,2-diol represented by general formula (10) as a material in this invention process are those in which R1 is hydrogen or C1-C6 alkyl, such as ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol; preferably ethylene glycol and 1,2-propanediol; more preferably ethylene glycol.
Commercially available 1,2-diol may be used as it is, or may be subject to a common purification process such as distillation before being used in the reaction.
Monoalkylamine represented by general formula (6) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 200 moles, preferably 0.5 to 80 moles, more preferably 1.0 to 40 moles per one mole of 1,2-diol.
The amount of carbon dioxide is generally, but not limited to, 0.1 to 200 moles, preferably 1 to 100 moles per one mole of 1,2-diol.
Alkylcarbamate alkylamine salt represented by general formula (7) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 100 moles, preferably 0.5 to 40 moles, more preferably 1.0 to 20 moles per one mole of 1,2-diol.
Then, 1,3-dialkylurea represented by general formula (8) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 100 moles, preferably 0.5 to 40 moles, more preferably 1.0 to 20 moles per one mole of 1,2-diol.
a)Monoalkylamine and carbon dioxide, b)alkylcarbamate alkylamine salt and c)1,3-dialkylurea may be used alone or concurrently or as a mixture.
Most preferably, ethylene glycol can be used as a 1,2-diol, monomethylamine can be used as a monoalkylamine, methylcarbamate methylamine salt can be used as an alkylcarbamate alkylamine salt and 1,3-dimethylurea can be used as a 1,3-dialkylurea, in the light of extensive applications of the product DMI therefrom as a solvent.
According to this invention, 1,3-dialkyl-2-imidazolidinones can be also prepared by heating at 50xc2x0 C. or higher 1,2-diol represented by general formula (10) with alkylcarbamate alkylamine salt represented by general formula (7) and/or 1,3-dialkylurea represented by general formula (8) in the presence of carbon dioxide, in a reactor whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glass.
The 1,2-diol represented by general formula (10) may be the same as described above.
Alkylcarbamate alkylamine salt represented by general formula (7) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 100 moles, preferably 0.5 to 40 moles, more preferably 1.0 to 20 moles per one mole of 1,2-diol.
The 1,3-dialkylurea represented by general formula (8) may be the same as described above. The amount thereof is generally, but not limited to, 0.1 to 100 moles, preferably 0.5 to 40 moles, more preferably 1.0 to 20 moles per one mole of 1,2-diol.
The reaction is conducted in an atmosphere of carbon dioxide. The atmosphere of the reaction is preferably of carbon dioxide. The amount of carbon dioxide is generally, but not limited to, 0.1 to 1000 moles, preferably 1 to 500 moles per one mole of 1,2-diol.
Alkylcarbamate alkylamine salt and 1,3-dialkylurea may be used alone or concurrently or as a mixture.
Most preferably, ethylene glycol can be used as a 1,2-diol, methylcarbamate methylamine salt can be used as an alkylcarbamate alkylamine salt and 1,3-dimethylurea can be used as a 1,3-dialkylurea, in the light of extensive applications of the product DMI therefrom as a solvent.
A reactor used in the process of this invention is one whose area in contact with at least part of the reactants and/or products is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glass. It may be, for example, wholly made of a metal comprising titanium or zirconium. Alternatively, at least part of the inside wall of the reactor is coated with a metal comprising titanium or zirconium or an oxide thereof, or the inside wall may be coated with inorganic glass. Examples of a metal comprising titanium or zirconium are industrial pure titaniums of JIS Types 1 to 4; corrosive resistant titanium alloys such as Tixe2x80x940.15Pd, Tixe2x80x945Ta and Tixe2x80x940.3Moxe2x80x940.8Ni; xcex1-type titanium alloys such as Tixe2x80x942.5Sn, Tixe2x80x945Alxe2x80x942.5Sn, Tixe2x80x945Alxe2x80x942.5Sn(ELI), Tixe2x80x942.5Cu, Tixe2x80x9420xe2x80x941Nxe2x80x945Fe, Tixe2x80x945Nixe2x80x940.5Ru, Tixe2x80x940.5Pdxe2x80x943Co and Tixe2x80x945.5Alxe2x80x943.5Snxe2x80x943Zrxe2x80x941Nbxe2x80x940.3Moxe2x80x940.3Si; near xcex1-type titanium alloys such as Tixe2x80x948Alxe2x80x941Moxe2x80x941V, Tixe2x80x942.25Alxe2x80x9411Snxe2x80x945Zrxe2x80x941Moxe2x80x940.2Si, Tixe2x80x946Alxe2x80x942Snxe2x80x944Zrxe2x80x942Mo, Tixe2x80x945Alxe2x80x945Snxe2x80x942Zrxe2x80x942Moxe2x80x940.25Sn, Tixe2x80x946Alxe2x80x942Nbxe2x80x941Taxe2x80x940.8Mo, Tixe2x80x946Alxe2x80x945Zrxe2x80x940.5Moxe2x80x940.2Si and Tixe2x80x944.5Alxe2x80x943Vxe2x80x942Fexe2x80x942Mo; xcex1+xcex2 type titanium alloys such as Tixe2x80x945Alxe2x80x942Crxe2x80x941Fe, Tixe2x80x945Alxe2x80x945Snxe2x80x945Zrxe2x80x942Crxe2x80x941Fe, Tixe2x80x944Alxe2x80x944Mn, Tixe2x80x943Alxe2x80x942.5V, Tixe2x80x946Alxe2x80x944V, Tixe2x80x946Alxe2x80x944V(ELI), Tixe2x80x946Alxe2x80x946Vxe2x80x942Sn, Tixe2x80x946Alxe2x80x942Snxe2x80x944Zrxe2x80x946Mo, Tixe2x80x947Alxe2x80x944Mo, Tixe2x80x945Alxe2x80x942Zrxe2x80x944Moxe2x80x944Cr, Tixe2x80x946Alxe2x80x941.7Fexe2x80x940.1Si, Tixe2x80x946.4Alxe2x80x941.2Fe, Tixe2x80x9415Zrxe2x80x944Nbxe2x80x942Taxe2x80x942Pd, Tixe2x80x946Alxe2x80x947Nb and Tixe2x80x948Mn; xcex2 type titanium alloys such as Tixe2x80x9413Vxe2x80x9411Crxe2x80x943Al, Tixe2x80x9415Moxe2x80x945Zr, Tixe2x80x9415Moxe2x80x940.2Pd, Tixe2x80x9415Vxe2x80x943Crxe2x80x943Snxe2x80x943Al, Tixe2x80x9420Vxe2x80x944Alxe2x80x941Sn, Tixe2x80x9422Vxe2x80x944Al and Tixe2x80x9416Vxe2x80x944Snxe2x80x943Alxe2x80x943Nb; near xcex2 type titanium alloys such as Tixe2x80x9410Vxe2x80x942Fexe2x80x943Al and Tixe2x80x949.5Vxe2x80x942.5Moxe2x80x943Al; pure zirconium; and zirconium alloys such as zircaloy-2, zircaloy-4, Zrxe2x80x942.5Nb and Ozenite; preferably titanium-containing metals and pure zirconium; more preferably industrial pure titanium, corrosion resisting titanium alloys and pure zirconium. The content of titanium or zirconium in the metal comprising titanium or zirconium or the oxide thereof is generally at least 30 mol %, preferably at least 50 mol %, more preferably at least 60 mol % to the whole metal elements. The inside wall may be coated with the metal by a process selected from cladding, baking, flame spray coating, vapor deposition, decomposition and any combination thereof. Among them, cladding processes such as rolling, explosive compaction, explosive rolling and casting rolling as well as baking process may be preferably employed. The inside wall may be coated with an oxide film by the process of thermal decomposition, baking, flame coating, forming an oxide film on the metal surface of the inside wall of the reactor using an oxidizing agent or a combination thereof. Among others, preferable processes are, for example, PdO/TiO2 coating by thermal decomposition of PdCl2 and TiCl3, or forming an oxide film using an oxidizing agent such as oxygen-containing gases including oxygen and air; peroxides including hydrogen peroxide and peracetic acid; and nitric-acid agents including nitric acid and a mixture of nitric acid and hydrofluoric acid. The oxide film may be formed on the inside wall of the reactor before conducting the reaction. Alternatively, the oxide film may be formed by incorporating an oxidizing agent in the reaction system, while heating alkylene carbonate, N-alkylmonoethanolamine or 1,2-diols with monoalkylamine and carbon dioxide, alkylcarbamate alkylamine salt and/or 1,3-dialkylurea. These coating methods may be further combined. For example, the inside wall may be coated with a metal comprising titanium or zirconium by the process of cladding or baking or a combination thereof, followed by forming an oxide film over the metal surface using an oxidizing agent.
A reactor comprising inorganic glasses may be a reactor wholly made of inorganic glasses, a metal reactor in which an inorganic glass cup is placed, or a metal reactor lined with inorganic glass; preferably a metal reactor lined with inorganic glass.
Inorganic glasses in the present invention are a glassy state of inorganic material such as elemental glasses, hydrogen-bonding glasses, oxide glasses, fluoride glasses, chloride glasses, sulfide glasses, carbonate glasses, nitride glasses and sulfate glasses; preferably oxide glasses including silicate glass, phosphate glass and borate glass; particularly, silicate glasses including silica glasses such as quartz glass, silicate alkali glasses such as water glass, soda-lime glasses such as sheet glass and crown glass, potash lime glasses such as Bohemian glass and crystal glass, lead glasses such as flint glass, barium glasses such as barium flint glass and borosilicate glasses such as electrical glass; more preferably, soda-lime glasses; most preferably, soda-lime glasses containing aluminum, magnesium or calcium ion as a modifying ion.
Preferably, 50 to 100%, more preferably 80 to 100% of the area in contact with reactants and/or products is made of (I) a metal comprising titanium or zirconium or (II) inorganic glass. More preferably, the whole reactor including a gas phase region is made of (I) a metal comprising titanium or zirconium and/or an oxide thereof or (II) inorganic glasses, although a reactor comprising (I) rather than (II) is preferable for a reaction conducted at a pressure of 5 MPa or higher.
A style of the process of this invention is not particularly limited, and may be any style in which materials used are effectively mixed and contacted with each other, including a batch, semi-batch or continuous flow type. For example, all materials may be placed in a reactor together; at least one material may be continuously or intermittently added to the other materials; or all materials are continuously or intermittently fed into a reactor.
In the process of this invention, reactants are heated at 50xc2x0 C. or higher, preferably at 50 to 400xc2x0 C., more preferably 100 to 300xc2x0 C.
A reaction time and a pressure may vary depending on the amount of materials, a reaction temperature and other factors, but a reaction time is generally up to 200 hours, preferably 0.01 to 100 hours, more preferably 0.1 to 50 hours. The reaction is generally conducted under a pressure, preferably at 0.1 to 50 MPa, more preferably 0.2 to 20 MPa.
A gas used for replacing or pressurizing a reaction system may be, but not limited to, an inert gas such as nitrogen and argon or preferably carbon dioxide. Carbon dioxide may be used as a gaseous, liquid or solid state, or may be introduced as an inorganic carbonate such as ammonium carbonate which generates carbon dioxide during the reaction.
In the process of this invention, a reaction is generally conducted without solvent, but may be conducted in the presence of a solvent. Any solvent which does not adversely affect the reaction may be used. Solvents which may be used include water; aliphatic and alicyclic hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene and xylenes; aliphatic and aromatic halogenated compounds such as dichloromethane, chloroform, fluorobenzene, chlorobenzene and dichlorobenzene; ethers such as diethyl ether, methyl tert-butyl ether, dibutyl ether, diphenyl ether, tetrahydrofuran, dioxane and ethylene glycol diethyl ether; ketones such as acetone, diethyl ketone; methyl isobutyl ketone and acetophenone; nitrites such as acetonitrile and propionitrile; nitro compounds such as nitromethane, nitrobenzene and nitrotoluene; esters such as ethyl acetate and ethyl propionate; carbonates such as dimethyl carbonate; noncyclic and cyclic amides such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone; cyclic urea compounds such as 1,3-dialkyl-2-imidazolidinones including DMI (the product of the process of this invention); and supercritical fluids such as supercritical carbon dioxide. Further, these solvents may be used alone or in combination of two kinds or more at the same time, and if such solvents be used, the reaction may be carried out in a multi-layer system of two or more layer solvents. Among these solvents, 1,3-dialkyl-2-imidazolidinone, which is the product of the process of this invention, and water are preferable.
Such a solvent may be used at an amount sufficient to dissolve at least one of the starting materials, generally up to 100 parts by weight, preferably up to 50 parts by weight per one part of alkylene carbonates, N-alkyl monoethanolamines, or 1,2-diols, a starting material.
In the process of this invention, a catalyst and/or an additive may be added for improving an yield and a reaction rate.
In the process of this invention, at the end of the reaction, a reaction mixture may be worked up as usual, for example, via distillation, to give 1,3-dialkyl-2-imidazolidinones. The 1,3-dialkyl-2-imidazolidinone thus obtained includes 50 ppm or less of 1-alkoxyalkyl-3-alkyl-2-imidazolidinone which is a common impurity in a conventional process, and 0.5 wt % or less of N-alkylformamide.